Energy conversion devices, such as electric motors and transformers may be less than 100% efficient, and the efficiency shortfall may appear in the form of heat or thermal energy. This heat energy may be transferred to the environment (e.g., air) with adequate efficiency such that components within the device do not become excessively hot. The average rate of heat production (thermal power) for conversion devices may be approximately proportionate to the average through-power of the device. Accordingly, for such devices, the continuous power rating may be determined by the efficiency of heat transfer between heat dissipating components within the device and the ambient environment. As heat transfer is improved, the continuous rating may be increased, and the utility of the device thereby enhanced. Thus, there is a need for a structure which has general utility in connection with heat transfer applications, and which specifically applies to electric machines, transformers, and other magnetic components.